Process for the preparation of graphene

Abstract

The present invention provides a process for the preparation of graphene or graphene-like fragments of another layered structure, said process comprising the step of mixing and grinding graphite or said other layered structure with at least one ionic liquid. The invention also provides the use of grinding in ionic liquids in such a process and products formed or formable by such methods.

Description

FIELD OF THE INVENTION[0001]The present invention relates to processes for the preparation of graphene and graphene-like structures. In particular, the invention relates to processes for the preparation of graphene in the absence of redox reactants, and most particularly to physical methods of preparation. The invention also relates to the graphene produced by such processes and to the use of such processes in the preparation of graphene.BACKGROUND[0002]Graphene is a single atom thick planar sheet of sp2-bonded carbon atoms which are positioned in a honeycomb crystal lattice. The term “graphene” is also used to represent structures having a small number of graphene layers and similar properties. The distinctive structure of graphene confers many unique mechanical, electronic, thermal, optical and magnetic properties upon it, in addition to quantum effects that have never been found in other materials. For example, the charge carriers in graphene behave as massless Dirac fermions and...

AI Technical Summary

Benefits of technology

[0019]Viewed from another aspect, the invention provides a graphene nanodot having a height of 1 to 3 nm. Optionally, and preferably, these graphene nanodots have a diameter of less than 10 nm. The graphene nanodots of the invention may be formed by or formable by a process as hereinbefore described.

Problems solved by technology

However, currently explored chemical solution exfoliation methods have a number of drawbacks that need to be addressed.

The addition of foreign molecules to graphene is, however, undesirable for many applications and leads to the graphene produced by these chemical exfoliation methods being quite poor in quality compared to that fabricated by CVD and micromechanical cleavage.

This is mainly because the various chemicals used, such as solvents, oxidants and reductants may attack the graphene lattice in the process or are difficult to be removed, leading inevitably to residual surface species.

Overall these chemical processes introduce various forms of surface defects, which disrupt the graphene band structure and hamper the conductivity of the resulting graphene sheets.

Another disadvantage of the known chemical exfoliation methods is that many of the chemicals used are either expensive or toxic and need careful handling, leading to environmentally unfriendly and unsustainable approaches.

Furthermore, the majority of chemical solution exfoliation methods involve extremely time-consuming multiple steps that sometimes last for several days.

In addition, thermal reduction is most successfully carried out at ˜1000° C., a temperature which is unsuitable for many applications.

However the yield of this process is small and not appropriate for mass scale production.

However, the graphene sheets produced by these simple techniques still contain a few impurities (such as fluorine, sulphur etc.), and a large fraction of oxygen (more than 10 at %) similar to that found in graphene reduced from graphene oxide.

Oxygen in graphene is difficult to be removed and may significantly influence the property and application of graphene.

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